The present invention is directed to a method of regulating speed of a longitudinally or axially moving fiber particularly a light waveguide as well as to an apparatus for implementation of the method.
Speed regulating methods are utilized, for example, in the manufacture of light waveguide cables. After a glass fiber has been drawn, additional worksteps are performed on the fiber such as providing a protective cladding, injecting the fiber with a filling compound into a sheath and/or stranding a plurality of fibers to form a cable. In order to take a greater coefficient of thermal expansion of the cladding compared to the light waveguide into consideration, the latter is shot in with a precise metered excess length. A German published application OS DE No. 31 11 963 shows an example of such a manufacturing process. The significance of an exactly meterable braking effect in conjunction with the shrinkage during cooling clearly proceeds from this published application. However, at the beginning of the manufacturing process, the light waveguide is only slightly protected. Mechanical stresses can easily cause additional attenuations. One must therefore proceed with extreme caution in the regulation of the speed of movement of the fiber. At present, magnetic, disk and felt brakes and the like are utilized as braking devices.
However, these types of braking devices have yet other disadvantages. Fibers of any type that are drawn off overhead are easily twisted. Brakes that do not function contact-free tend to back up the twist, and when working with sensitive fibers such as, for example, light waveguides, there is a risk that they will tear. Given more flexible fibers, this backup of the twist can lead to a loop formation which is also undesirable.